The invention generally relates to the field of the design configuration of a circuit breaker which is used in low-voltage networks. It may be related to one which is applicable to the configuration of the bearing for the integral switching shaft of such a switch.
Low-voltage circuit breakers have one or more switch poles. The switching contact systems, which include fixed and movable switching contacts, of these switch poles are normally mechanically connected to coupling levers, which are arranged on a switching shaft which is common to all the switch poles.
For such a circuit breaker to operate correctly, it is essential for the switching shaft to have radially precise bearings, with little axial play. A known bearing arrangement which is suitable for this purpose has, in the region of the coupling levers, a bearing assembly which is connected to a housing front wall of the switch pole and contains a bearing body with a cylindrical bearing surface. The production of the switching shaft and its installation are simplified by subdivision into two symmetrical subelements. Each subelement is provided with a radial bearing and an axial bearing at one end by means of the main bearing body. Two further auxiliary bearing bodies are required for the complete axial bearing.
In the case of an integral switching shaft, such a shaft would be permanently connected to the main bearing body by the coupling levers, which are arranged in fixed positions on both sides of the main bearing body. If the main bearing body is faulty, the entire switching shaft must be replaced together with it (DE 197 39 702 C1).
In another known bearing arrangement, the integral switching shaft, which is fitted with all the coupling levers, can be prepositioned in its installed position, independently of the bearing assembly. In this case, the switching shaft is positioned in recesses, which are open at the edges, in walls which are arranged at right angles to the longitudinal axis of the switching shaft. One shaft bearing, which includes two half shells, is then inserted in the axial direction into each of the recesses. Such a shaft bearing provides a radial bearing for the switching shaft away from the points at which the switching forces act. The location of the axial bearing is not mentioned (DE 44 16 090 C1).
An embodiment of the invention includes an object of designing the bearing assembly such that the switching shaft, which is already prepositioned in its installed position and is provided with the coupling levers, is mounted at the point where the switching forces act. This can be done in a manner such that it is insensitive to tolerances and is convenient for assembly.
According to an embodiment of the invention, an object can be achieved by the bearing body being mounted on the housing front wall of the switch pole, surrounding the switching shaft in the form of a half shell, and by a first subregion of the bearing body being arranged between the coupling levers and forming side guide surfaces for the coupling levers which are connected to the switching shaft.
This configuration allows the bearing assembly and the switching shaft to be replaced independently of one another at any time.
In this case, the bearing assembly has a simple construction and can thus be produced cost-effectively. In addition, it is compact and can thus be installed easily and in a space-saving manner. In addition, the switching shaft bearing can be very largely independent of tolerances, since the switching shaft uses the same bearing body for both radial and axial bearing.
Stops for the on and off positions of the switching contacts can be provided easily, according to one development of the invention, in that a second subregion of the bearing body projects axially beyond the coupling levers and forms stop surfaces for the coupling levers.
If the catch hook, which is normally used in an arrangement such as this, is mounted in a window-like recess in the bearing body such that it can pivot, and the mating piece is in the form of a bolt which passes through the coupling levers, this additional element is integrated in a space-saving manner in the bearing assembly.
One arrangement designed according to the invention for the switching shaft bearing is expediently used in multipole low-voltage circuit breakers in such a way that a bearing assembly at each of the two ends of the switching shaft is associated with the axially outer movable switching contacts. The switching shaft bearing is thus defined statically.